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<Orders>
<Order>
<OrderNo>18090</OrderNo>
<Article>09</Article>
<Data>
<Column>1</Column>
</Data>
</Order>
</Orders>
if you use xs:choice then you may get any order and several element may be several times inside of <Order> but you cannot make some elements to be required
if you use xs:all then you may make some elements to be required and you may get any order but element may be no more than once inside of <Order>
Checking online[edit | edit source]
http://www.utilities-online.info/xsdvalidation/#.VqoVWbcrKCr